Experts estimate about 800 babies' lives could be saved each year if all women quit smoking during pregnancy.
Mothers who smoke during pregnancy are more than twice as likely to have babies die suddenly in their sleep as women who avoid tobacco, a USA study suggests.
Of those live births, more than 19,000 deaths over the four-year period were attributed to SUID, caused by sudden infant death syndrome (SIDS), an unknown cause or accidental suffocation and strangulation in bed, researchers found.
To see how smoking while pregnant affected the likelihood of SUID, the researchers examined data from almost 20 million births between 2007 and 2011 while also taking into consideration mothers' smoking habits.
The research likewise demonstrated moms who smoked three months before pregnancy and quit in the primary trimester still had a higher danger of SUID contrasted and non-smokers.
"With this information, doctors can better counsel pregnant women about their smoking habits, knowing that the number of cigarettes smoked daily during pregnancy significantly impacts the risk for SUID", said Dr. Tatiana Anderson, a researcher in Seattle Children's Center for Integrative Brain Research and lead author on the study.
However, the good news is that women who reduced their smoking by the third trimester benefited from a 12 per cent reduction in the risk of SUID compared with those who continued smoking, and those who quit smoking altogether saw a 23 percent reduction in risk.
Beyond overall cigarette consumption, the researchers also looked at how smoking before pregnancy, and cutting back or quitting smoking during pregnancy, affected SUID risk. Smoking by mothers, fathers and anyone else around pregnant women and babies may increase not just the risk of SUID but also childhood asthma and respiratory illnesses, Goodstein added.
"Since many women who smoke during pregnancy continue to smoke after they deliver, it is a little hard to separate out the effects of prenatal and postnatal cigarette smoke exposure", said Dr. Michael Goodstein, division chief of WellSpan Health Neonatology in York, Pennsylvania.